It is known to employ a cotton knit sock (e.g., single jersey knit) as a first layer and cotton or poly/cotton webbing for cushioning (also called padding) as a second layer under a hard shell casting material. Known casting materials are either of fiberglass or plaster-of-paris. In use, the known castliner comprises a cotton jersey sleeve, which is pulled over the limb being treated, and a cotton webbing wrapped around the limb. Typically, some skill is required for application of the castliner of this known type. Particular skill is needed during application of the layers of cotton webbing, which is cumbersome to apply. Especially important is the required thickness of cotton webbing which ultimately protects the limb during the cast removal process. A particular disadvantage of such known castliners is their poor water repellency and moisture transmission rate. Water retention by known castliners fosters the growth of bacteria causing patient complaints about: unpleasant odors, itching, and general discomfort.
An improvement to the foregoing known cotton cast lining is described in U.S. Pat. No. 5,540,964 to Mallen. Mallen discloses a cast lining which is capable of transporting moisture from beneath the cast to the air space within the cast and ultimately to the outside area. In one embodiment of the Mallen invention a fabric is formed from a blend of hydrophobic synthetic fibers (e.g., polyester) and a second fiber (spandex). This fabric is constructed into a tube with or without open ends and used as castliner beneath an orthopedic cast. Mallen's cast lining tube is then made “hydrophilic” according to methods disclosed therein. In general, the Mallen fabric conforms closely to the limb being treated due to the elastic fiber content of the tubular cast lining. Mallen specifically discloses use of LYCRA® (branded spandex from INVISTA S.à r.l. of Wilmington, Del.) in its construction.
Applicants have found various prior art cast lining materials disadvantageous in several modes of performance. First, jersey knit sleeve and cotton webbing can be difficult for unskilled casting room operators to apply uniformly. Second, the moisture absorption of these sleeve and webbing liners is high. Third, the sleeve and webbing lining can be stiff and can provide pressure points at joints especially. The Mallen (U.S. Pat. No. 5,540,964) cast lining is an improvement in conformance to the limb shape.
It would be desirable to improve cushioning and moisture transmission rate while minimizing the pressure points caused by elastic yarns in the construction. Typically, points of increased pressure on the limb are present in areas of the limb joints and where the limb changes diameter most abruptly.
Thus, a longstanding unmet need for a sleeve-like knitted castliner without the deficiencies of the prior art exists.